Cyclones off northern Australia typically develop between 5 and 15°S and reach maximum intensity between 10 and 20°S. As they move further south they will weaken over land or, for those remaining over water, weaken as they encounter an unfavourable environment (strengthening wind shear) and move over cooler water. They usually increase in speed as the steering winds in the mid-levels of the atmosphere increase and move to the south or southeast.